The present invention relates to a dynamo-electric machine control system for controlling a motor and a generator, and a vehicle driving system including the dynamo-electric machine control system.
In recent years, hybrid vehicles having both an engine and a dynamo-electric machine (a motor or a generator) as driving force sources have come to attention due to concerns about the environment and energy consumption. In this type of hybrid vehicle, the dynamo-electric machine is connected to a battery for supplying electric power to the dynamo-electric machine, and a current flowing to the dynamo-electric machine is controlled by an inverter interposed between the dynamo-electric machine and the battery. Here, when an excessive current is drawn from the battery to the inverter, problems such as a reduction in the durability of the battery and damage to a switching device or the like may occur, and therefore a torque of the dynamo-electric machine is sometimes limited under fixed conditions.
For example, Japanese Patent Application Publication No. JP-A-2005-210779 describes that a dynamo-electric machine control system has a dynamo-electric machine and an inverter that is interposed between a battery and the dynamo-electric machine and controls a current flowing through the dynamo-electric machine, and in the dynamo-electric machine control system, a rotation speed and an output torque of the dynamo-electric machine are controlled by the inverter. In this dynamo-electric machine control system, a limit power of a predetermined magnitude (having a fixed value) is set. The dynamo-electric machine control system estimates a battery power from a sum of a power consumed by the dynamo-electric machine when operating at the rotation speed and output torque, and a rate of change in a stored power of a smoothing capacitor annexed to a circuit constituting the inverter. The dynamo-electric machine control system then limits a torque command relating to the dynamo-electric machine to ensure that the estimated battery power does not exceed the predetermined limit power. Hence, a situation in which an excessive current is drawn from the battery can be prevented while taking into consideration variation in the stored power of the smoothing capacitor.